The production of semiconductor devices often involves forming microelectronic devices on a microelectronic substrate, such as a silicon wafer. Such microelectronic devices may include for example transistors, resistors, capacitors, combinations thereof, and the like, which may be connected to one another and other components via a metallization pattern (e.g., metal interconnects), so as to form one or more integrated circuits.
Various processes are known for forming integrated circuits on a microelectronic substrate. Among those processes is the so-called “damascene process,” which typically involves using a photoresist and etching processes to selectively remove material from the microelectronic substrate or other dielectric material. For example, the photoresist may be patterned on a dielectric material, after which the dielectric material may be etched to form a hole or “trench” (hereinafter, opening) consistent with the photoresist pattern. After etching, the photoresist may be removed (e.g., using an oxygen plasma or selective wet/dry etching) and the opening may be filled with a conductive material such as a metal or metal alloy, e.g., via physical vapor deposition, chemical vapor deposition, electroplating, or some other mechanism as will be understood to those skilled in the art.
Over time the size of microelectronic devices has shrunk dramatically, while the complexity of such devices has increased. As a result it is becoming increasingly difficult to form various features (e.g., vias, via plugs, traces, etc.) using existing photolithographic techniques, such as those that may be used in a Damascene process. Indeed in many cases semiconductor manufacturing engineers are now tasked with forming features on one or more layers of a semiconductor device/substrate, wherein such features have at least one dimension that is smaller than the wavelength of light used in an available photolithographic tool.
For example many photolithographic tools employ a laser (e.g., an excimer laser) to project an image of a feature to be formed on a substrate with deep ultraviolet (UV) light at a wavelength of about 248 nanometers (nm) or about 193 nm. Although useful, the feature size that may be reliably formed by such tools may be limited. For example, excimer UV photolithography may be used to produce features having a minimum features size of about 50 nm. While it is possible to use such tools to produce features with a minimum feature size less than 50 nm, doing so may be practically difficult for a variety of reasons. Moreover as features with ever smaller minimum feature size are becoming increasingly desirable, it may be increasingly important to form such features within increasingly tight tolerances. This may further exacerbate challenges associated with using some photolithographic tools to produce smaller and smaller features. Indeed even if certain tools may be used to produce features with a minimum feature size below 50 nm, such features may exhibit unacceptably high variance and therefore may be unable to meet one or more desired tolerances.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.